Dual-piston fluid pump

ABSTRACT

A multi-piston fluid pump system includes a pump head, a motor unit, and a processor, the pump head having two or more cylinders and a piston disposed within each cylinder, the motor unit configured to provide bi-directional actuation of the pistons in each cylinder in response to control signals from the processor in order to minimize fluctuations in pressure and/or flow rate at the outlet of the fluid pump system.

TECHNICAL FIELD

This disclosure relates generally to fluid pump systems and related systems and methods. Fluid pump systems are described herein in the context of medical fluid injection systems and associated actuation and control systems (e.g., as part of a contrast/saline injection system for medical imaging applications) as one exemplary type of application.

BACKGROUND

Medical fluid injection systems are used to deliver certain fluids (e.g., contrast media, saline, etc.) during cardiac angiography and other diagnostic imaging procedures.

Reciprocating pumps may be used for fluid delivery. One challenge in using a reciprocating pump design for medical applications is to deliver the fluid at desired flow rates and/or pressures, while minimizing pulsations and/or fluctuations in flow rate, pressure, etc., that may be commonly associated with reciprocating pump designs.

SUMMARY

In general, various embodiments relating to fluid pump systems and associated actuation and control systems and methods are disclosed herein. In particular, disclosed herein are embodiments of a reciprocating pump for delivering fluids during medical and/or diagnostic imaging procedures.

One embodiment includes a fluid pump system. The fluid pump system includes one or more pump heads, a motor unit, and a processor to control the operation of the fluid pump system. The pump head includes two cylinders, a piston within each cylinder configured to move bi-directionally within its respective cylinder, an inlet associated with each cylinder to facilitate filling of the respective cylinders, and an outlet for delivering fluid from both cylinders. The motor unit may include two motors, operably coupled to drive each of the pistons bi-directionally within the two cylinders. In embodiments having more than one motor, the motors may operate independently of each other, and may vary in certain operating characteristics, such as frequency, travel length, size, etc. The processor includes communication and/or control circuits for controlling the operation of the motor unit, and optionally, for controlling other aspects of the fluid pump system operation.

In some preferred embodiments, the processor is configured to move the fluid pump system through a sequence of phases of operation in order to deliver a relatively steady rate of fluid flow, while minimizing pulsations and/or fluctuations in fluid flow or pressure that may arise.

In a further embodiment of the fluid pump system, valves may be used to control the flow of fluid into and out of the cylinders during the various phases of operation of the fluid pump system. For example, each cylinder may have a valve at a respective inlet, and each cylinder may have a valve at a respective outlet.

Another embodiment includes active control of the timing of valve operation relative to the phases of operation of the fluid pump system. Other embodiments include one or more sensors to sense certain fluid delivery aspects, such as flow rate or pressure, and employ a feedback system (e.g., using closed-loop feedback control concepts) to continually or intermittently modify operating parameters of the fluid pump system (e.g., speed of piston movement, timing of transitions between operating phases, timing of valve openings and closures, etc.) in real-time to minimize fluid flow and/or pressure fluctuations/pulsations at the outlet of the fluid pump system.

In a further embodiment of the fluid pump system, a disposable pump head may be used. A disposable pump head may, for example, be replaced between successive patients or procedures. In some embodiments, the fluid pump system may use identifying information about the disposable pump head (e.g., manufacturing lot number, operating specification information, etc.) to adjust operating and timing parameters to account for manufacturing tolerances, for example, to achieve smoother flow characteristics at the pump system outlet. A possible embodiment includes a scanning feature (e.g., via RFID, infrared, integrated circuits with unique identifiers, or other known technologies) that automatically reads the identifying information from the disposable pump head and allows the fluid pump system to alter the programmed operating settings of the pump system based thereon.

The details of one or more examples are set forth in the accompanying drawings and the description below. Other features, objects, and advantages will be apparent from the description and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings are illustrative of particular embodiments of the present disclosure and therefore do not limit the scope of the invention. The drawings are intended for use in conjunction with the explanations in the following description. Embodiments of the invention will hereinafter be described in conjunction with the appended drawings, wherein like numerals denote like elements.

FIG. 1 is a schematic diagram showing the elements of an exemplary embodiment of a fluid pump system.

FIGS. 2A and 2B are time plots illustrating the relative contribution to fluid delivery from each cylinder of a fluid pump system according to some embodiments.

FIGS. 3A-3D are side views of cylinders and pistons of a fluid pump system showing the relative positions and movements of the respective pistons within the associated cylinders during various phases of operation of a fluid pump system.

FIG. 4 is a schematic diagram showing an embodiment of a fluid pump system employing a disposable and/or replaceable pump head.

FIGS. 5A and 5B are flow block diagrams illustrating the flow of information and control signals in open-loop and closed-loop feedback control configurations, respectively, of a fluid pump system in accordance with some embodiments.

FIGS. 6A, 6B, and 6C are schematic diagrams showing embodiments of a fluid pump system able to deliver fluids from multiple fluid sources.

DETAILED DESCRIPTION

The following detailed description is exemplary in nature and is not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the following description provides some practical illustrations for implementing embodiments of the present invention. Examples of constructions, materials, and/or dimensions are provided for selected elements. Those skilled in the art will recognize that many of the noted examples have a variety of suitable alternatives.

FIG. 1 is a schematic diagram showing an exemplary embodiment of a fluid pump system 100. As shown in FIG. 1 , fluid pump system 100 includes a pump head 200, a motor unit 400 operatively coupled to the pump head 200, and a processor 300, which is configured to control the motor unit 400.

In operation, according to the exemplary embodiment of FIG. 1 , the fluid pump system 100 may be used to inject a fluid into a patient, for example, into a vessel of a patient via a catheter. The fluid injected by the fluid pump system 100 can be, for example, a contrast fluid, a non-contrast fluid (e.g., saline), or a combination thereof. By injecting a quantity of fluid into a patient, the fluid pump system 100 can facilitate a variety of medical diagnostic and/or interventional procedures, including the collection of image data representing an anatomical region of interest. Such procedures can include, as examples, angiographic procedures, interventional device procedures/placements, intravascular ultrasound (IVUS) imaging, optical coherence tomography (OCT) imaging, computed tomography (CT) imaging, and magnetic resonance imaging (MM).

In the embodiment depicted in FIG. 1 , pump head 200 may include a first cylinder 202 and a second cylinder 204. The first cylinder 202 is shown having a first piston or plunger 206 operatively disposed within cylinder 202, and the second cylinder 204 is shown having a second piston or plunger 208 operatively disposed within cylinder 204. The pump head 200 further includes a first inlet 210 fluidly coupled to the first cylinder 202, a second inlet 212 fluidly coupled to the second cylinder 204, and an outlet 214 fluidly coupled to both the first cylinder 202 and the second cylinder 204.

Motor unit 400 is operatively coupled to pump head 200 and configured to actuate the first piston 206 bi-directionally within the first cylinder 202 and is configured to actuate the second piston 208 bi-directionally within the second cylinder 204. In the embodiment shown in FIG. 1 , the bi-directional actuation of the first and second pistons 206, 208 refers to movement of the pistons in both a delivery direction (e.g., toward outlet 214) and a filling direction (e.g., away from outlet 214).

In some embodiments, motor unit 400 could be comprised of two motors operatively coupled to actuate both the first piston 206 and the second piston 208. This could be accomplished, for example, through the use of gears and mechanical linkages as are known in the art. In the exemplary embodiment shown in FIG. 1 , motor unit 400 comprises a first motor 402 and a second motor 404. As shown, first motor 402 is configured to actuate first piston 206 bi-directionally within first cylinder 202, and second motor 404 is configured to actuate second piston 208 bi-directionally within second cylinder 204.

Processor 300 is configured to control the operation of motor unit 400 such that the total amount of fluid being delivered from the outlet 214 of the pump head 200 (the total delivered flow rate) is maintained at a target flow rate. The target flow rate may be selected by a user of the fluid pump system 100, or it may be determined based on certain criteria (e.g., a patient-specific protocol such as the patient's weight or creatinine level), or via an algorithm, (which, for instance, may define a predetermined combination of two or more of said criteria), etc.

Processor 300 is configured to control motor unit 400 to achieve the target flow rate from the outlet 214 of pump head 200 by causing a series of actions to occur. In some embodiments, the series of actions comprise a sequence of phases of operation. For example, during a first phase, processor 300 may cause motor unit 400 to actuate the first piston 206 in a first delivery direction to deliver fluid from first cylinder 202 through the outlet 214 at the target flow rate. In some embodiments, processor 300 may cause motor unit 400 to actuate second piston 208 in a second filling direction during the first phase to draw fluid into second cylinder 204 through second inlet 212. In certain embodiments, the motor unit 400 actuates the first piston 206 in the first delivery direction and actuates the second piston 208 in the second filling direction at substantially the same time (e.g., simultaneously) during the first phase.

At or near the end of the first phase, processor 300 may initiate a second phase of operation. During the second phase, motor unit 400 may actuate first piston 206 to continue moving in the first delivery direction to deliver fluid from the first cylinder 202, but at a decreasing speed or rate. Also during the second phase, motor unit 400 may actuate second piston 208 to move in a second delivery direction to deliver fluid from the second cylinder 204 at an increasing speed or rate. One result of the concurrent delivery of fluid from both the first and second cylinders 202, 204 is that the total delivered flow rate of fluid from the outlet 214 of pump head 200 is maintained relatively stable at or near the target flow rate during the second phase.

In certain embodiments, the second phase of operation may be characterized by having the relative contribution of fluid delivery from the first cylinder 202 decrease from approximately 100% of the target flow rate to approximately 0% of the target flow rate, while the relative contribution of fluid delivery from the second cylinder 204 increases from approximately 0% of the target flow rate to approximately 100% of the target flow rate.

In certain embodiments, the decrease and/or increase in fluid delivery from the first and second cylinders, 202 and 204 respectively, during the second phase can be linear or exponential in nature, or some other function of time.

As one example, FIG. 2A shows a time plot of fluid flow rate from the first and second cylinders 202, 204, through the outlet 214, where the decrease in fluid flow rate from the first cylinder 202 through outlet 214 during the second phase is a linear decrease from time t2 to t3 (labeled “A” in FIG. 2A), while the corresponding increase in fluid flow rate from the second cylinder 204 through outlet 214 during the second phase is a linear increase from time t2 to t3 (labeled “B” in FIG. 2A). The sum of the fluid flow rates from the first and second cylinders 202, 204 (the total delivered flow rate of fluid from the outlet 214, labeled “A+B” in FIG. 2A) is thereby maintained at a steady level, preferably close to the target flow rate.

As another alternative example, FIG. 2B shows a time plot of fluid flow rate from the first and second cylinders 202, 204, through the outlet 214, where the decrease in fluid flow rate from the first cylinder 202 through outlet 214 during the second phase is an exponential decrease from time t2 to t3 (labeled “A” in FIG. 2B), while the corresponding increase in fluid flow rate from the second cylinder 204 through outlet 214 during the second phase is an exponential increase from time t2 to t3 (labeled “B” in FIG. 2B). The sum of the fluid flow rates from the first and second cylinders 202, 204 (the total delivered flow rate of fluid from the outlet 214, labeled “A+B” in FIG. 2B) is thereby maintained at a steady level, preferably close to the target flow rate.

Note that in FIGS. 2A and 2B, only the contributions to fluid flow resulting from movement of the first or second pistons 206, 208 in the first and second delivery directions (e.g., toward the outlet 214) is plotted. Fluid flow in the first or second filling directions (e.g., away from outlet 214) is not plotted here since it does not contribute to the total delivered flow rate of fluid from the outlet 214 of the pump head. For example, during the first phase shown in FIGS. 2A and 2B, second piston 208 may move in a second filling direction to draw fluid into second cylinder 204. This flow of fluid is not represented in FIGS. 2A and 2B. It should also be noted that the use of the phrases “delivery direction” and “filling direction” are used in recognition of the fact that the arrangement of the first and second cylinders 202, 204 may not necessarily be side-by-side or parallel, as depicted in FIG. 1 , but could instead be in an “in-line” or angled arrangement such that the delivery direction of one cylinder need not necessarily be the same as (or parallel to) the delivery direction of the other cylinder, and similarly for the filling directions of the two cylinders.

Note also with respect to FIGS. 2A and 2B that the y-axis may depict flow rate (e.g., volumetric flow rate) on a relative basis; that is, the flow rates are shown to increase, or decrease, or stay steady at some value as a function of time, as shown. Alternately, the y-axis may represent pressure at the outflow 214 on a relative basis. It is not intended, for example, to illustrate that the flow rate from the first cylinder 202 is at all times greater than from the second cylinder 204. The flow rate contributions from the first and second cylinders 202 and 204 would normally be roughly equivalent over time, although embodiments where one is intentionally greater than the other may be implemented as well according to some alternate embodiments.

In some embodiments, processor 300 may be further configured to initiate a third phase of operation of fluid pump system 100 following the second phase. During a third phase, processor 300 may be further configured to cause motor unit 400 to actuate first piston 206 in a first filling direction to draw fluid into first cylinder 202 through the first inlet 210. In some embodiments, processor 300 may cause motor unit 400 to actuate second piston 208 in the second delivery direction to deliver fluid from the second cylinder 204 through outlet 214 at the target flow rate during the third phase. In certain embodiments, motor unit 400 actuates the first piston 206 in the first filling direction and actuates the second piston 208 in the second delivery direction at substantially the same time during the third phase.

At or near the end of the third phase, processor 300 may initiate a fourth phase of operation. During the fourth phase, motor unit 400 may actuate second piston 208 to continue moving in the second delivery direction to deliver fluid from the second cylinder 204 toward the outlet 214, but at a decreasing speed or rate. Also during the fourth phase, motor unit 400 may actuate the first piston 206 to move in the first delivery direction to deliver fluid from the first cylinder 202 through the outlet 214 at an increasing flow rate. One result of the concurrent delivery of fluid from both the first and second cylinders 202, 204 during the fourth phase is that the total delivered flow rate of fluid from the outlet 214 of pump head 200 is maintained relatively stable at or near the target flow rate during the fourth phase.

In certain embodiments, the fourth phase of operation may be characterized by having the relative contribution of fluid delivery from the first cylinder 202 increase from approximately 0% of the target flow rate to approximately 100% of the target flow rate, while the relative contribution of fluid delivery from the second cylinder 204 decreases from approximately 100% of the target flow rate to approximately 0% of the target flow rate. In certain embodiments, the decrease and/or increase in fluid delivery from the first and second cylinders, 202 and 204 respectively, during the fourth phase can be linear or exponential in nature, or some other function of time, as similarly described above with respect to the second phase.

In some embodiments, processor 300 may be configured to cause fluid pump system 100 to perform the four phases of operation repeatedly and/or in succession to deliver fluid in a continuous manner from outlet 214.

As used herein, processor 300 may be embodied in a single computing device or in a combination of one or more processing units, storage units, and/or other computing devices. Processor 300 may include, for example, one or more central processing units (“CPUs”), a system memory, a random access memory (“RAM”) and a read-only memory (“ROM”), and circuitry or hardware that couples the various forms of memory to the CPUs.

The first and second inlets 210, 212 are configured to fluidly couple the first and second cylinders, 202 and 204 respectively, to one or more sources (or reservoirs) of the fluid to be delivered by the fluid pump system 100. For example, in some embodiments, first inlet 210 and second inlet 212 may each be fluidly coupled to a single common reservoir of a fluid to be delivered by fluid pump system 100. The single common reservoir of fluid could supply, for example, a medical fluid such as a contrast agent, or a saline solution, or a mixture of contrast fluid and saline, or some other fluid (e.g., a drug, a medicine, a nutrient, . . . ). For example, a mixture may be prepared in advance and supplied within the given reservoir, and thus a mixture of fluids enters the pump in such an example. In certain other embodiments, there may be two independent reservoirs of fluid, each fluidly coupled to the first and second cylinders 202, 204 via the first and second inlets 210, 212. In such an embodiment, it may be desirable to have the two independent reservoirs of fluid contain the same type of fluid (e.g., both containing contrast agent, or both containing saline), or it may be preferable to have one fluid reservoir containing one type of fluid, and the other fluid reservoir containing a different type of fluid (e.g., contrast agent in one reservoir, saline in the other reservoir) such that the operation of fluid pump system 100 results in the delivery of alternating fluid types from outlet 214. This arrangement may, for example, allow for the delivery of a mixture of two different fluid types from the outlet 214 of fluid pump system 100. Delivering a mixture of two different fluid types may be desired in certain situations, for example small volume injections, where the injection procedure does not need to refill the two chambers, or if the two chambers are big enough to ensure that the injection procedure can be carried out and completed without having to refill the two chambers.

Motor unit 400 may comprise a single motor operatively adapted to move first piston 206 and second piston 208 via appropriate gearing and linkages as are known in the art. In some embodiments, motor unit 400 may comprise two motors. With reference to FIG. 1 , motor unit 400 may comprise a first motor 402 and a second motor 404, the first motor configured to actuate the first piston 206 bi-directionally within first cylinder 202. With reference to FIG. 1 , motor unit 400 may comprise a second motor 404 configured to actuate second piston 208 bi-directionally within second cylinder 204. In some embodiments, processor 300 may be configured to actuate first motor 402 independently of second motor 404, for example via signal 310 (e.g., an electrical signal). In some embodiments, processor 300 may actuate first and second motors 402, 404 to move first and second pistons 206, 208 to deliver a total delivered flow rate of fluid from the outlet 214 at a target flow rate. Preferably, the total delivered flow rate is maintained substantially at the target flow rate by processor 300 providing an appropriate signal or signals 310 to motor unit 400, or to each of the first and second motors 402 and 404.

First and second motors 402, 404 could each be either a rotary motor or a linear motor, and they need not both be of the same type of motor. For example, first or second motor 402, 404 could be a rotary motor type with a lead screw arrangement configured to actuate its corresponding first or second piston 206, 208 to move within its corresponding first or second cylinder 202, 204. Alternatively, first or second motor 402, 404 could be a linear motor type, for example, configured to actuate its corresponding first or second piston 206, 208 to move within its corresponding first or second cylinder 202, 204. A non-limiting example of a linear motor type is a voice-coil motor or voice-coil actuation (“VCA”) motor.

In an embodiment employing a rotary motor design for motor 402 or 404, the rotary motor may be controlled by a servo motor controller, for example, wherein rotary movement is converted to linear movement by a rotating lead screw. In an embodiment employing a linear motor direct drive design for motor 402 or 404, such as a VCA motor or non-commutated DC linear actuator, such a motor comprises a permanent magnetic portion and a coil assembly adapted to conduct electric current therethrough. Electric current flowing through the coil assembly interacts with the permanent magnetic portion to generate a force that is perpendicular to the direction of the current. Additionally, the direction of the force can be reversed by changing the polarity of current flowing through the coil assembly. These aspects of a VCA motor (non-commutated DC linear actuator) may provide certain benefits that may enhance the ability of fluid pump system to minimize fluctuations, such as precise control of piston position, high acceleration/deceleration rates, and potentially smoother transitions due to the elimination of gearing/coupling, etc.

In certain embodiments, it may be desirable for pump head 200 to be a disposable (e.g., replaceable every new injection/patient, or of limited use which means that it is replaced after a predetermined period of time has lapsed) component of fluid pump system 100. For example, in medical fluid delivery applications, fluid pump system 100 may comprise motor unit 400 and processor 300 as permanent components of fluid pump system 100, while pump head 200 may be a disposable component that must be replaced after each use. This could be important in medical fluid delivery applications, for example, where a disposable pump head 200 may allow for the use of new, sterile pump head 200 prior to performing a medical fluid delivery operation with a given patient, and it may allow for the removal of the pump head 200 following a medical fluid delivery operation with a given patient (and before using fluid pump system 100 with a different patient). This may, for example, aid in the prevention of cross-contamination between successive patients. In the context of a disposable pump head, the term “disposable” may refer to a limited use or single use pump head that is specifically designed to be replaced between procedures and/or between patients to reduce the risk of cross-contamination.

When using a disposable pump head 200, independent control of motors 402 and 404 by processor 300 may allow for fluid pump system 100 to adjust for differences and/or tolerances (e.g., manufacturing tolerances) between successive disposable pump heads 200, and to thereby continue to maintain the total delivered flow rate of fluid from outlet 214 at or near the target flow rate while minimizing variations and pulsations in the flow rate of fluid from outlet 214. The adjustment for differences and/or tolerances (e.g., manufacturing tolerances) between successive disposable pump heads 200 may, for example, comprise a software adjustment which is performed by processor 300.

A fluid pump system 100 may additionally include one or more valves for controlling the flow of fluid. For example, in the embodiment depicted in FIG. 1 , a number of valves may be used to control the flow of fluid. As shown, a first valve 220 may be positioned to control fluid flow between the first inlet 210 and the first cylinder 202. First valve 220 may, for example, be in the open position to allow filling of first cylinder 202 from a fluid reservoir (not shown) coupled to inlet 210. First valve 220 may, for example, be in the closed position to allow delivery of fluid from first cylinder 202 toward outlet 214.

As shown in FIG. 1 , a second valve 222 may be positioned to control fluid flow from the first cylinder 202 toward outlet 214. Second valve 222 may, for example, be in the open position to allow delivery of fluid from first cylinder 202 toward outlet 214. Second valve 222 may, for example, be in the closed position to facilitate filling of first cylinder 202 from a fluid reservoir (not shown).

As shown in FIG. 1 , a third valve 224 may be positioned to control fluid flow from the second cylinder 204 toward outlet 214. Third valve 224 may, for example, be in the open position to allow delivery of fluid from second cylinder 204 toward outlet 214. Third valve 224 may, for example, be in the closed position to facilitate filling of second cylinder 204 from a fluid reservoir (not shown).

As shown in FIG. 1 , a fourth valve 226 may be positioned to control fluid flow between the second inlet 212 and the second cylinder 204. Fourth valve 226 may, for example, be in the open position to allow filling of second cylinder 204 from a fluid reservoir (not shown) coupled to inlet 212. Fourth valve 226 may, for example, be in the closed position to allow delivery of fluid from second cylinder 204 toward outlet 214.

Any or all of first valve 220, second valve 222, third valve 224, and fourth valve 226 can be comprised of a check valve, which opens to allow fluid to flow through the valve in only one direction, and which closes to prevent fluid from flowing in the opposite direction. For example, first valve 220 and fourth valve 226 are located in first and second inlets 210 and 212, respectively. Each of first valve 220 and fourth valve 226 opens to allow fluid to flow into first and second cylinders 202 and 204, respectively, and closes to prevent fluid from flowing back out of the inlets 210, 212 of both cylinders 202, 204. Second and third valves 222 and 224 function in an analogous manner. Examples of check valves that could be used include ball-type check valves, stop check valves, lift check valves, globe valves, butterfly valves, etc.

In alternate embodiments, any or all of first valve 220, second valve 222, third valve 224, and fourth valve 226 can be comprised of an actively-controlled valve. An actively-controlled valve may, for example, respond to a signal from processor 300 to open or close. For example, signal 320 in FIG. 1 schematically represents such a signal being sent from processor 300 to pump head 200 to actively control the opening or shutting of a valve or valves. Examples of actively-controlled valves may include motor-operated valves or solenoid-operated valves. A pinch-valve design is an example of a valve that could be actively-controlled by operation of a motor or by operation of a solenoid. It should be noted that signal 320 may also include signals sent to processor 300 with information about a condition or operating parameter of the fluid pump system 100, such as information about the position of valves 220, 222, 224, and 226, or the positions of pistons 206, 208, or other operating parameters or conditions of the fluid pump system.

In an exemplary embodiment, valves 220, 222, 224, and 226 may be comprised of pinch valves that operate by pinching (to shut/close) or releasing (to open) a portion of a disposable pump head 200. This may be accomplished by using fluid tubing portions in the design and/or construction of pump head 200, for example. In such an embodiment, a fluid tubing portion of pump head 200 may be operably engaged or seated within an associated pinch valve, and the pinch valve would be configured to pinch or release the fluid tubing to shut or open the valve, respectively. For example, in some embodiments, fluid pump system 100 may comprise a disposable pump head 200 that includes one or more fluid tubing portions. When such a disposable pump head 200 is positioned or installed as part of fluid pump system 100, the one or more fluid tubing portions are configured to engage and become operable with one or more pinch valves arranged as part of fluid pump system 100. Such an arrangement may offer certain benefits to users of fluid pump system 100, which may include better prevention of cross-contamination between patients, ease of setting up fluid pump system 100 between successive patients, and associated savings in time and/or cost.

In embodiments of fluid pump system 100 where processor 300 is employed to actively control the opening and/or shutting of valves 220, 222, 224, and 226, processor 300 may be configured or programmed to precisely control the timing of the opening and/or shutting of valves 220, 222, 224, and 226 relative to the phases of operation of fluid pump system 100, for example. Control over the timing of valve operation relative to the phases of operation may, for example, be useful to help minimize fluctuations or pulsations in fluid flow and/or pressure at the outlet 214 of fluid pump system 100.

It may be desirable, for example, to have a valve change its position, when appropriate, synchronously with the transition from one phase to the next. For example, during a transition from phase 3 to phase 4 as described above (e.g., transition from filling first cylinder 202 to delivering fluid from first cylinder 202 at an increasing rate) and with reference to first cylinder 202, first valve 220 would be actively shut, second valve 222 would be actively opened, and first piston 206 would change direction from the filling direction to the delivery direction all at substantially the same time. In some alternate embodiments, it may be determined to be preferable to have some offset in the timing of the valve actuation relative to the change in phase in order to better minimize fluctuations or pulsations in fluid flow and/or pressure at outlet 214. It may be determined (for example, during design testing or manufacturing testing) that slightly delaying the opening or shutting of a valve until just after the phase transition will help minimize fluctuations at the outlet 214. Conversely, it may be determined that opening or shutting an affected valve slightly before the phase transition will work better to minimize flow or pressure fluctuations. Further, it may be the case that operating one valve before the phase transition and the other valve after the transition works best to minimize fluctuations. It should be noted that some of these variations could be due to manufacturing differences or tolerances, and that a particular “lot” of pump heads 200 might warrant using one set of timing offsets, while a different lot should use a different set of timing offsets to achieve comparably low levels of flow/pressure fluctuation at outlet 214.

Regarding manufacturing differences or tolerances in disposable pump heads, as noted above, there may be characteristics of each specific manufacturing lot that warrant making adjustments (e.g., implemented in software via processor 300) to various operating parameters (e.g., timing of valve actuation, speed of piston movement, etc.) in order to minimize flow/pressure fluctuations at outlet 214 during anticipated use. This lot-specific variability may be measured and/or accounted for in a number of ways. During the manufacturing process, testing may be performed prior to release of each given lot of a disposable product to empirically determine a set of adjustments that may be particular to all units (e.g., disposable pump heads 200) from the same lot. All units produced from a given lot could be assigned a common lot number, which may be printed on associated labeling for the product, or which could be encoded using an automatic scanning feature or technique. In a case where the lot number is printed on a label, a user could manually enter the lot number into system 100 prior to use, and appropriate adjustments to operating parameters could be implemented by processor 300 in response thereto. Alternately, if the lot number is encoded using an automatic identification or scanning technique (e.g., through RFID, infrared, or through the use of integrated circuits (“IC”) such as EEPROMs having unique identifiers), the lot number could be determined automatically, and any corresponding parameter adjustments could be readily implemented by processor 300 (e.g., via software). It is also possible that the parameter adjustments themselves could be provided directly by the automatic scanning technology, rather than (or in addition to) the lot number; this might eliminate, for example, the need for processor 300 to “look-up” the parameter adjustments that correspond to a certain lot number, or eliminate the need for system 100 to receive periodic updates with information about new lots, etc.

In some optional embodiments of a fluid pump system according to the invention, a fifth valve 230 may be positioned to control fluid flow at the outlet 214 of fluid pump system 100. Fifth valve 230 may, for example, be useful to restrict or limit fluid delivery from fluid pump system 100 during unexpected conditions, such as a high pressure or high flow condition at outlet 214. A high pressure or high flow condition may be sensed by a sensor 240 placed at or near outlet 214, for example. In such an embodiment, sensor 240 may provide a measurement reading (e.g., a measured pressure or a measured flow rate) to processor 300 via a sensor signal 330. Processor 300, in response to receiving a measurement reading (sensor signal 330) from sensor 240 exceeding some predetermined threshold value (e.g., a default safety setting, or a user-selected value), may initiate a corrective action, which might include one or more of the following: slowing or stopping the delivery of fluid by reducing the speed of the first and/or second pistons in the delivery direction; shutting the second and/or third valves 222, 224 to restrict fluid flow towards outlet 214; and partially or completely shutting valve 230 to restrict fluid flow from outlet 214. Safety considerations addressed may include, for example, avoiding movement of a catheter tip caused by pressure fluctuations, which could cause damage to coronary arteries during angiographic imaging applications as one example. Additionally, very high pressures, if not avoided, could ultimately cause damage and/or bursting of a patient line or catheter. The use of a measurement reading (e.g., via a sensor signal 330 from a sensor such as sensor 240) to avoid exceeding a predetermined value is an example of closed-loop feedback control employed for safety considerations in some embodiments.

In some alternate embodiments, valve 230 may alternately, or additionally, function as a “shut-off” valve to enable use of system 100 in multi-patient applications. In such an embodiment, valve 230 would be disposed proximal to (upstream of) a patient line or catheter (not shown) to prevent the potential for contamination (e.g., cross-contamination between successive patients). In an optional embodiment, disposable pump head 200 may be configured for multi-patient use (e.g., limited to a single day use, or to a specified maximum number of patients, or to a limited period of time, etc.). In such an optional embodiment, outlet 214 may be configured to be a separate, single-use (e.g., limited to use with a single patient) component of system 100 that releasably connects to disposable pump head 200, and which comprises valve 230. Using both multi-use and single-use components as part of system 200 may provide an additional level of isolation and may thereby further protect from the possibility of contamination between patients and/or procedures.

In some embodiments, a sensor, such as sensor 240 in FIG. 1 , may be employed to implement or facilitate closed-loop control of fluid pump system 100 to improve upon its ability to reduce any fluctuations or pulsations in the fluid flow or pressure at the outlet. In such an embodiment, sensor 240 may provide a measurement reading (e.g., a measured pressure or a measured flow rate at outlet 214, for example) to processor 300 via a sensor signal 330. Processor 300, in response to receiving the measurement reading (sensor signal 330) from sensor 240, may be configured to adjust one or more operating parameters of fluid pump system 100 to achieve the desired or programmed target flow rate. Such adjustments may occur repeatedly, for example, in an effort to continuously strive to achieve the target flow rate. The adjustments may comprise, for example, increasing or decreasing the speed of one or both pistons 206, 208 (by varying the speed of motors 402 and 404, for example), or by varying the timing of the transitions from one phase to the next successive phase, or by varying the timing of the opening or closing of certain valves with respect to the phases of operation of fluid pump system 100.

In some embodiments, sensor 240 may provide a pressure measured at outlet 214, for example, and processor 300 may be configured to control motor speeds and/or valve positions in order to avoid exceed a maximum pressure limit (e.g., a user-defined setting, or a pre-determined maximum) for safety reasons.

In some embodiments, certain valves may have the ability to partially restrict flow or “throttle” flow. In such embodiments, processor 300 may control the positions of one or more of valves 222, 224, and 230 in order to achieve a target flow rate while minimizing pulsation or fluctuation in flow or pressure. Processor 300 may, for example, employ closed-loop feedback to actively modify the positions of valves 222, 224, and 230 to attempt to achieve the desired flow characteristics, including the use of partially-open or throttled positions of the appropriate valve or valves.

In FIGS. 3A-3D, the relative positions of the first and second pistons within the first and second cylinders is shown at the beginning and end of each phase.

FIG. 3A shows the relative positions and movements of the first and second pistons 206 and 208 within first and second cylinders 202 and 204 during a first phase of operation of fluid pump system 100. For example, during a first phase, first piston 206 moves in a delivery direction (to the right in FIG. 3A) at a relatively constant speed that corresponds to the target flow rate. During this phase, piston 206 moves from a first intermediate position 262 to a second intermediate position 264 within first cylinder 202, while second piston 208 moves in a filling direction (to the left in FIG. 3A) from a fully-extended position 266 to a fully-retracted position 260. In some embodiments, this may involve the second piston 208 moving in a filling direction at a speed greater than the first piston 206 moves in the delivery direction (since it must travel a greater distance in approximately the same amount of time).

FIG. 3B shows the relative positions and movements of the first and second pistons 206 and 208 within first and second cylinders 202 and 204 during a second phase of operation of fluid pump system 100. For example, during a second phase, first piston 206 moves in a delivery direction (to the right in FIG. 3B) from the second intermediate position 264 to the fully-extended position 266 at a decreasing speed that decreases from a speed corresponding to approximately the target flow rate, to a speed of approximately zero, while second piston 208 moves in a delivery direction (to the right in FIG. 3B) from a fully-retracted position 260 to the first intermediate position 262 at an increasing speed that increases from approximately zero to a speed corresponding to approximately the target flow rate.

FIG. 3C shows the relative positions and movements of the first and second pistons 206 and 208 within first and second cylinders 202 and 204 during a third phase of operation of fluid pump system 100. For example, during a third phase, first piston 206 moves in a filling direction from a fully-extended position 266 to a fully-retracted position 260 within first cylinder 202, while second piston 208 moves in a delivery direction (to the right in FIG. 3C) from a first intermediate position 262 to a second intermediate position 264 within second cylinder 202 at a relatively constant speed that corresponds to the target flow rate. In some embodiments, this may involve the first piston 206 moving in a filling direction at a speed greater than the second piston 208 moves in the delivery direction (since it must travel a greater distance in approximately the same amount of time).

FIG. 3D shows the relative positions and movements of the first and second pistons 206 and 208 within first and second cylinders 202 and 204 during a fourth phase of operation of fluid pump system 100. For example, during a fourth phase, first piston 206 moves in a delivery direction (to the right in FIG. 3D) from a fully-retracted position 260 to the first intermediate position 262 within first cylinder 202 at a speed that increases from approximately zero to a speed corresponding to approximately the target flow rate, while second piston 208 moves in a delivery direction (to the right in FIG. 3D) from the second intermediate position 264 to the fully-extended position 266 at a decreasing speed that decreases from a speed corresponding to approximately the target flow rate to a speed of approximately zero.

The transition of fluid pump system 100 from one phase of operation to the next may be controlled by processor 300 in some embodiments. Signals 320 and/or 330, for example, may provide information about the condition of fluid pump system 100 and/or of pump head 200 to processor 300 that, in turn, causes processor 300 to end the current phase and begin the next phase, or to modify an operating parameter of fluid pump system 100, such as a motor speed or a valve position, for example. In some embodiments, the information about the condition of fluid pump system 100 may include information about pump head 200, including information about the position of the first piston 206 within first cylinder 202, or about the position of the second piston 208 within second cylinder 204. In some other embodiments, the information about the condition of fluid pump system 100 and/or pump head 200 may comprise information about the amount of time that has elapsed during the current phase. In some embodiments, the information about the condition of fluid pump system 100 and/or pump head 200 may comprise a measurement reading, such as sensor signal 330 from sensor 240, which may include measurements of flow rate or pressure at outlet 214, for example. In still other embodiments, the information about the condition of pump head 200 may comprise information about the amount of fluid remaining in the first or second cylinders 202, 204 (e.g., information about the amount of fluid remaining in a cylinder may be provided by a motor encoder and/or a position sensor). In some alternate embodiments, processor 300 may modify an operating parameter or condition of fluid pump system 100, or transition the fluid pump system 100 from one phase to the next, based on a logical combination of the foregoing conditions of fluid pump system 100 and/or pump head 200.

In some embodiments, processor 300 may be configured to ensure that certain combinations of valve positions are achieved and/or maintained during certain phases of operation of fluid pump system 100. For example, processor 300 may, during a first phase of operation, ensure that first valve 220 is shut, second valve 222 is open, third valve 224 is shut, and fourth valve 226 is open. Similarly, processor 300 may, during a second phase of operation, ensure that first valve 220 is shut, second valve 222 is open, third valve 224 is open, and fourth valve 226 is shut, etc.

In embodiments where phases and phase transitions are determined without regard to measured pressure or flow at the outlet 214, this level of control may be referred to as “open-loop” feedback control. Under open-loop feedback control, for example, the processor 300 may control the operation of fluid pump system 100 by following the sequence of phases in a repeating fashion, to control and/or use feedback information about the fluid pump system 100, such as information regarding the positions of the first and second pistons 206, 208, or the positions of valves 220, 222, 224, and 226, or the speed of motors 402, 404, or any combination of the above, etc. This “open-loop” control terminology could apply to the control of the positions of valves 220, 222, 224, and 226 in relationship to the positions of the pistons 206 and 208, for example. In one example, the processor 300 may modify the speed of the first motor 402 in response to information about the speed of the second motor 404. In another example, the speed of the first and/or second motors may be modified in response to information about the positions of the first and/or second pistons 206, 208. In other possible examples, the processor 300 may modify the speed of first and/or second motors and/or the position of one or more of valves 220, 222, 224, and 226 in response to information about the positions of the first and second pistons 206, 208. The modifications of operating conditions or parameters described herein are exemplary only and other potential modifications to operating conditions or parameters could be made by the processor 300 to achieve or maintain the phases of operation of the fluid pump system 100 and/or the corresponding transitions between phases.

On the other hand, a “closed-loop” feedback method of control may be employed to allow for adjustments to be made to any of the aforementioned parameters (e.g., the speed of piston movement or motor speed, or the timing of valve openings or closures, or the respective positions of the pistons, etc.) in response to a feedback signal or measurement, such as from a measurement of pressure and/or flow at the outlet 214. Such a “closed-loop” feedback control methodology may be useful, for example, in embodiments of a fluid pump system 100 that employ a disposable pump head 200 that may introduce manufacturing tolerances and other minor variations from one unit to the next. The use of closed-loop feedback control may also be helpful to remediate patient-related or patient-specific fluid pathway resistance variations, such as those caused by variations in catheter/needle tolerance, patient line length, patient blood flow resistance, etc. In some embodiments, closed-loop feedback control may be configured to enable or implement a “smart” injector system that relies less (or not at all) on user inputs regarding disposable types, manufacturing lot numbers, contrast media types, etc., and could thereby eliminate most or all errors resulting from such input steps, in addition to improving the speed and efficiency of the overall workflow.

It may be desirable to have initial operating parameters for fluid pump system 100 that are based on a “perfect” open-loop control model, and possibly one or two levels of refinement could be made available to better achieve the goal of minimizing fluctuations in flow/pressure. One level of refinement could be to obtain information about the “lot” or “batch” from which a disposable pump head 200 was manufactured, to enable making an adjustment in operating parameters to account for known aspects associated with that lot or batch. These adjustments could be made manually (by a user) or automatically (e.g., through RFID or other known scanning techniques or features). An example of this type of automatic adjustment may involve the use of an integrated circuit (“IC”) having a unique identifier (“ID”), such as the EEPROMs (electrically erasable programmable read-only memory) described at https://www.microchip.com/en-us/products/memory/serial-eeprom/mac-address-and-unique-id-eeproms. However, these types of adjustments would be made at the time of installation or utilization of disposable pump head 200 and would therefore still be deemed a form of open-loop control. Another level of refinement (either stand-alone or in combination with the previously described refinement) is to add “closed-loop” control by enabling the processor 300 to receive signals from one or more sensors, such as sensor 240, and to adjust operating parameters “on the fly” in response to such signals in order to achieve the desired flow characteristics.

Examples of open-loop and closed-loop control systems are illustrated in the conceptual flow block diagrams in FIGS. 5A and 5B.

FIG. 5A is a block diagram illustrating an example of an open-loop control design. In such a design, the timing of motor actuation and valve operation is typically initially predetermined (an initial “trajectory”), such as the trajectory of motor operation, piston movement, and valve operation described above with respect to the phases of operation of fluid pump system 100. At a system level, the trajectory may be determined (or possibly refined) based on the disposable type or batch/lot number, the contrast media type, the range of desired flow rates, etc. Once the initial trajectory has been determined, the system may rely on a motor drive board control loop to execute it. During operation, adjustment of certain operating parameters may occur to maintain the trajectory during operation.

FIG. 5A shows processor 300 comprising motor drive board 302, system firmware 304, and/or system software 306 in one example. The initial trajectory can be calculated at either a software level 306 or firmware level 304. In the example shown in FIG. 5A, the positions 206′ and 208′ (of first and second pistons 206, 208) may be communicated (via signals 322, 324) to processor 300 (e.g., to motor drive board 302 of processor 300) before starting operation and/or can be transferred to motor drive board 302 continuously in real-time during operation. Likewise, processor 300 (e.g., via motor driver board 302) provides signals 312 and 314 to motors 402 and 404 to drive pistons 206 and 208 in accordance with the desired trajectory. In normal conditions, at any given time, the positions of pistons 206, 208 are determined in accordance with the trajectory. However, deviations from the ideal trajectory may occur, and the processor can make adjustments or modifications to various operating parameters (e.g., motor speeds, timing of valve openings and closures, etc.) in order to maintain the basic trajectory of operation such that the phases transition appropriately and the desired flow characteristics are achieved. The benefit of such an open-loop control design may include potentially simplified design/implementation (hardware and firmware) and use of off-the-shelf components, as possible examples. Similarly, open-loop control may apply to the use of information about other portions of the fluid pump system. For example, rather than the positions 206′ and 208′ of first and second pistons 206, 208, information about the speed of the first and second motors 402, 404, or information about the positions of one or more valves 220, 222, 224, and 226, may be communicated to processor 300, and processor 300 may adjust or modify an operating parameter in response thereto.

It may be possible, however, to further improve the ability of pump system 100 to adjust to pulsations or fluctuations in flow rate and/or pressure at the outlet 214 due to, for example, manufacturing tolerances, or to the possibility of user errors such as inputting an incorrect fluid type or flow rate, or to other factors, for example.

FIG. 5B is a block diagram illustrating an example of a closed-loop control design. In such a design, while the initial trajectory may be somewhat pre-determined (e.g., the initial piston positions during the various phases of operation, the initial motor speeds, the valve positions and timing of changes, etc.), a sensor 240 at the outlet 214 of fluid pump system 100 may provide real-time feedback (e.g., pressure or flow rate or flow velocity, etc.) to processor 300 (e.g., to system firmware 304 and/or system software 306), and the trajectory can be updated in a continual feedback loop, for example, to minimize or prevent fluctuations in pressure or flow rate or flow velocity. The implementation of closed-loop versus open-loop control can be more challenging because it typically requires higher performance hardware (such as FPGA or high-performance micro-controllers) to perform the trajectory calculations quickly enough, may involve performing more complex software/firmware algorithms, may increase costs (e.g., due to use of disposable sensors), or may affect the reliability of sensor readings. Despite these potential constraints, the use of closed-loop feedback control may enable fluid pump system 100 to accommodate the use of disposable components (e.g., disposable pump head 200, for example) with different manufacturing tolerances, for example, and to accommodate other variables such as simple user error in the setup of fluid pump system 100, which may help achieve more consistent performance. Additionally, the use of closed-loop feedback control may enable the use of lower cost disposable components due to the potential ability to adjust to a wide range of manufacturing and/or design tolerances, for example.

It should be noted that, if implemented, closed-loop control should not affect the basic concepts illustrated in FIGS. 2A and 2B. That is, the timing sequence illustrated in FIGS. 2A and 2B remain valid regardless of whether an open-loop control or a closed-loop control method of feedback is employed. The difference is that, with closed-loop control, some operating parameters, such as the motor speeds, or the duration of certain phases of operation (e.g., the corresponding acceleration and/or deceleration of pistons during intermediate phases), or the timing of valve openings and closures, can be modified in “real-time” (e.g., continually, to achieve the desired flow characteristics at the outlet 214).

As an example, if one considers the time period between t2 and t3 of FIG. 2A, if the pressure sensor 240 reports a pressure or flow rate reading at or near outlet 214 that is too high, processor 300 would receive this information (via signal 330), and in response, would try to decrease pressure or flow rate to compensate. One approach in this circumstance would be to decrease acceleration of the second piston 208 while maintaining the deceleration of the first piston 206. Therefore, at time t3, the overall flow rate would reach a lower value achieving a smoother transition. Of course, an alternative approach in the same circumstance might be to maintain the acceleration rate of the second piston 208 and increase the deceleration rate of the first piston 206. However, this might result in the first piston 206 reaching a zero flow level earlier than t3 so that the trajectory of other components might be disrupted and/or need to be recalculated accordingly. Of course, there are many other variations on how processor 300 might respond to signal 330 from sensor 240, as would be apparent to one of ordinary skill in the art.

In FIG. 1 , an initial or preliminary phase may precede the four phases of operation described above. For example, prior to beginning the first phase, one or more initial conditions may be obtained by actions controlled by processor 300. In some embodiments, second cylinder 204 may be filled (e.g., due to movement of second piston 208 in the filling direction), and/or first piston 206 may be moved in the delivery direction at an increasing rate (e.g., linearly, exponentially, or otherwise) such that at the completion of such an initial phase, the various components of fluid pump system 100 are ready and able to begin the first phase (and successive phases thereafter). Similarly, it may be the case that fluid pump system 100 performs an initial phase that prepares it to begin the second, third, or fourth phase, depending on the operational status of fluid pump system 100 when beginning operation. For example, if the fluid pump system operation was stopped in the middle of the third phase, it may be desirable to employ an initial phase at the outset of the next injection that places the system ready to begin a fourth phase of operation, and so on.

In certain embodiments, it may be desirable to deliver a medical fluid in “puffs,” or brief bursts of fluid delivery. This may be helpful, for example, in medical imaging applications where it may be desirable to deliver a puff of contrast media in a general location within a patient to provide an overall view of an area of interest, and to potentially help identify a more particular area of interest. In anticipation of such a puff injection, a fluid pump system 100 may possess the ability to temporarily depart from the four phases of operation described above. For example, in some embodiments, this could involve the actuation and movement of a single piston at a faster speed. The other piston need not be filling during a puff injection, so the motor unit 400 may be able to deliver additional power or speed to a single piston to accomplish a puff injection. Alternately, a puff injection may be accomplished via the simultaneous delivery of fluid from both cylinders. To prepare for this type of puff injection, it may be desirable to at least partially fill both cylinders in advance, then shut both inlet valves 220, 226 and open both outlet valves 222, 224 to achieve a higher fluid flow capability useful for a puff injection. In this embodiment, both cylinders may be filled in advance in anticipation of a puff injection by simultaneously moving both cylinders in a filling direction; this would involve, for example, shutting both outlet valves 222, 224, and opening both inlet valves 220, 226 prior to the filling operation.

Following a puff injection, processor 300 may be configured to either (a) prepare for subsequent puff injections, or (b) prepare to resume normal four-phase operation of fluid pump system 100.

Processor 300 may be configured to provide fluid pump system 100 with certain safety features. For example, during operation of fluid pump system 100, a “watchdog” software program can separately perform repeated checks or comparisons of delivered flow volumes to a patient to ensure that safety limits are not exceeded. A safety limit may, for example, be determined or calculated by processor 300 based on information provided about a specific patient, such as weight, age, gender, health history, etc., in order to minimize or prevent an overdose risk. In the context of imaging applications, contrast media overdose is a major safety risk and can lead to acute kidney injury (AKI). User errors and cybersecurity issues may possibly introduce additional potential for similar types of overdose risk. A watchdog software program may therefore be configured to operate independently of normal operation to monitor a parameter, such as total volume of fluid delivered, and take action (e.g., provide a warning or an indication to a user, or slow or stop the delivery of fluid, etc.) to help ensure patient safety.

FIG. 4 is a schematic block diagram illustrating an embodiment of fluid pump system 100 employing a disposable pump head 200. (Certain internal aspects of disposable pump head 200, such as cylinders and plungers, etc., are not shown in FIG. 4 to avoid unnecessary detail or duplication, although they are part of pump head 200 as previously described with respect to FIG. 1 herein.) As shown in FIG. 4 , fluid pump system 100 may comprise a portion that is a relatively “permanent” unit or system, and a portion that is disposable or replaceable and/or intended for single or limited use. In the embodiment shown in FIG. 4 , a disposable pump head 200 is shown next to the more permanent parts of the fluid pump system 100, including processor 300, motor unit 400, and fluid pump body 102. Fluid pump body 102 may be adapted to operably engage with disposable pump head 200, for example via mechanical latches or connectors as are known in the art. For example, mechanical couplings, fittings, connectors, etc., as are known in the art, may be employed to operably couple first and second motors of motor unit 400 to corresponding first and second pistons of pump head 200, according to some embodiments. In some embodiments, disposable pump head 200 may snap or click into a releasable mechanical engagement with fluid pump body 102, for example. In the particular embodiment illustrated in FIG. 4 , a series of pinch valve heads 220 a, 222 a, 224 a, 226 a, and 230 a may be arranged to receive tubing associated with disposable pump head 200 and corresponding to inlets 210 and 212 and outlet 214 of disposable pump head 200. Accordingly, operation of any of pinch valve heads 220 a, 222 a, 224 a, 226 a, and 230 a would result in either shutting or opening the corresponding valve (e.g., pinching or releasing the tubing in the corresponding valve locations). The pinch valves could be operated by known means, for example, by a solenoid actuation mechanism. A solenoid actuation mechanism may provide a potential safety benefit in the event of a loss of power to fluid pump system 100; loss of power to the solenoids, for example, may result in pinching shut all associate tubing and/or valves, and preventing fluid flow into or out of fluid pump system 100.

FIGS. 6A-6C are schematic diagrams illustrating embodiments of a fluid pump system 100 that could be employed, for example, to deliver fluids from multiple fluid sources. Such embodiments of a fluid pump system could accordingly be configured to deliver a mixture of fluids including a mixture of different fluid types.

In the embodiment shown in FIG. 6A, for example, the fluid pump system comprises two motor units 6400, 6401, and two pump heads 6200, 7200, that feed into a common downstream outlet 6214. The pump heads 6200, 7200, could each be arranged to deliver a particular fluid type (e.g., one pump head could deliver saline, the other could deliver contrast agent). In such an embodiment, the mixture ratio (e.g., the percent contrast content) of fluid delivered at the downstream outlet 6214 could be varied by separately controlling the target flow rates of each of pump heads 6200, 7200. For example, delivering contrast from one pump head at a flow rate of 6 mL/sec, while simultaneously delivering saline from the other pump head at a flow rate of 4 mL/sec would yield a net total flow rate at outlet 6214 of 10 mL/sec of a 60% contrast solution. Other mixture ratios and flow rates could be readily achieved by varying the above parameters as would be apparent to one of ordinary skill in the art with the benefit of these teachings.

FIG. 6B shows an alternate embodiment of a fluid pump system that may accomplish a similar goal of delivering fluids from multiple fluid sources, including, for example, a mixture of fluid types, by using a “Y-connector” at the inlet of one or more of the cylinders (or syringes) of the fluid pump system. In one exemplary arrangement shown in FIG. 6B, motor unit 6400 is operably coupled to pump head 6200, as in earlier described embodiments, and the mixing of fluids may be accomplished via the respective inlets of the respective cylinders. As one possible example, one Y-connector could provide fluids from two sources (e.g., two fluid types) at the inlet to one syringe such that, during a filling of the respective cylinder (e.g., due to movement of the respective plunger in a filling direction within the cylinder/plunger), the two fluids are drawn into the cylinder with some level of mixing occurring during the filling of the cylinder. On a subsequent fluid delivery (e.g., due to movement of the respective plunger in a delivery direction within the cylinder/plunger), the mixture of the two fluids is delivered toward the outlet, where it may be further mixed and delivered with the fluid delivered from the opposite cylinder. As shown, both cylinders could be arranged with Y-connectors to effect a similar mixing of fluids at the respective inlets, but this is not essential. In further embodiments, a Y-connector may include two separate valves leading to the two fluid sources as shown in FIG. 6B, which may enable control of the mixing by, for example, shutting one of the two valves, or by opening both, or by intermittently opening and shutting one of the two valves to introduce the desired proportion of the fluid type from that particular source. This could also be done at either or both of the Y-connector inlets, for example. Other comparable arrangements for delivering a mixture of fluid types would become apparent to one of ordinary skill in the art with the benefit of these teachings.

FIG. 6C shows an embodiment that may accomplish the delivery of a mixture of fluids by using a combination of a two-cylinder fluid pump system (e.g., having one or two fluid types at the inlets of the two cylinders) operated in conjunction with a single-cylinder fluid pump system with one of the two fluid types, or with a potentially different fluid type from a single fluid type delivered by the two-cylinder fluid pump. Other comparable arrangements for delivering a mixture of fluid types would become apparent to one of ordinary skill in the art with the benefit of these teachings.

Various non-limiting exemplary embodiments have been described. It will be appreciated that suitable alternatives are possible without departing from the scope of the examples described herein. These and other examples are within the scope of the following claims. 

What is claimed is:
 1. A fluid pump system comprising: a pump head comprising a first cylinder and a second cylinder, the first cylinder having a first piston disposed within, and the second cylinder having a second piston disposed within; a first inlet fluidly coupled to the first cylinder, and a second inlet fluidly coupled to the second cylinder; an outlet fluidly coupled to the first cylinder and to the second cylinder; a motor unit operatively coupled to the pump head, the motor unit comprising a first motor and a second motor, the first motor configured to actuate the first piston bi-directionally within the first cylinder, and the second motor configured to actuate the second piston bi-directionally within the second cylinder; and a processor configured to control the motor unit such that a total delivered flow rate of fluid from the outlet of the pump head is maintained at a target flow rate, the processor configured to: during a first phase, cause the motor unit to actuate the first piston in a first delivery direction to deliver fluid from the first cylinder through the outlet at the target flow rate, while causing the motor unit to actuate the second piston in a second filling direction to draw fluid into the second cylinder through the second inlet; and during a second phase, cause the motor unit to actuate the first piston in the first delivery direction to deliver fluid from the first cylinder through the outlet at a first decreasing flow rate, while causing the motor unit to actuate the second piston in a second delivery direction to deliver fluid from the second cylinder through the outlet at a second increasing flow rate such that the total delivered flow rate of fluid from the outlet of the pump head is maintained substantially at the target flow rate during the second phase.
 2. The fluid pump system of claim 1 wherein the processor is further configured to: during a third phase, cause the motor unit to actuate the first piston in a first filling direction to draw fluid into the first cylinder through the first inlet, while causing the motor unit to actuate the second piston in the second delivery direction to deliver fluid from the second cylinder through the outlet at the target flow rate; and during a fourth phase, cause the motor unit to actuate the second piston in the second delivery direction to deliver fluid from the second cylinder through the outlet at a second decreasing flow rate, while causing the motor unit to actuate the first piston in the first delivery direction to deliver fluid from the first cylinder through the outlet at a first increasing flow rate such that the total delivered flow rate of fluid from the outlet of the pump head is maintained substantially at the target flow rate during the fourth phase.
 3. The fluid pump system of claim 2 wherein the processor is configured to actuate the first motor independently of the second motor.
 4. The fluid pump system of claim 3 wherein the first motor and the second motor are each comprised of one of a rotary motor with a lead screw and a linear motor.
 5. The fluid pump system of claim 3 wherein the pump head is a disposable component of the fluid pump system.
 6. The fluid pump system of claim 3, further comprising: a first valve for controlling fluid flow between the first inlet and the first cylinder; a second valve for controlling fluid flow between the first cylinder and the outlet; a third valve for controlling fluid flow between the second cylinder and the outlet; and a fourth valve for controlling fluid flow between the second inlet and the second cylinder.
 7. The fluid pump system of claim 6 wherein at least one of the first, second, third, and fourth valves is a check valve.
 8. The fluid pump system of claim 6 wherein at least one of the first, second, third, and fourth valves is an actively-controlled valve.
 9. The fluid pump system of claim 8 wherein the at least one actively-controlled valve is configured to be controlled by the processor.
 10. The fluid pump system of claim 9 wherein the pump head is a disposable pump head, and wherein at least one of the actively-controlled valves is a pinch valve assembly configured to act upon a portion of the disposable pump head.
 11. The fluid pump system of claim 3 wherein the processor is configured to cause the first, second, third, and fourth phases to repeat in succession.
 12. The fluid pump system of claim 3 wherein each of the first increasing flow rate, the first decreasing flow rate, the second increasing flow rate, and the second decreasing flow rate are comprised of one of a linearly changing rate and an exponentially changing rate.
 13. The fluid pump system of claim 3 wherein the processor is configured to modify an operating parameter or condition of the fluid pump system in response to information about a condition of the fluid pump system comprising one of: (a) a first position of the first piston within the first cylinder, (b) a second position of the second piston within the second cylinder, (c) an elapsed time since the initiation of the current phase, (d) an amount of fluid remaining in the first cylinder or the second cylinder, and (e) any logical combination of conditions (a) through (d).
 14. The fluid pump system of claim 6 wherein the processor is configured to modify an operating parameter or condition of the fluid pump system in response to information about a condition of the fluid pump system comprising one of: (a) a first position of the first piston within the first cylinder, (b) a second position of the second piston within the second cylinder, (c) an elapsed time since the initiation of the current phase, (d) an amount of fluid remaining in the first cylinder or the second cylinder, (e) a position of one or more of the first, second, third, and fourth valves, and (f) any logical combination of conditions (a) through (e).
 15. The fluid pump system of claim 8 further comprising a sensor proximate the outlet, the sensor configured to provide a sensor signal to the processor, and the processor configured to modify either or both of a motor unit operating parameter and a position of any of the first, second, third, or fourth valves in response to the sensor signal.
 16. The fluid pump system of claim 15 wherein the sensor is a pressure sensor, and the processor is configured to modify either or both of the motor unit operating parameter or the position of any of the first, second, third, or fourth valves to avoid exceeding a maximum pressure limit.
 17. The fluid pump system of claim 15 wherein the sensor is a flow sensor, and the processor is configured to modify either or both of the motor unit operating parameter or the position of any of the first, second, third, or fourth valves to achieve the target flow rate at the outlet.
 18. The fluid pump system of claim 15 wherein the processor is configured to modify the timing of changes to the positions of any of the first, second, third, or fourth valves to minimize fluctuations in flow or pressure at the outlet.
 19. The fluid pump system of claim 9 wherein information about the disposable pump head is provided to the processor and used to determine one or more initial operating parameters of the fluid pump system.
 20. A method of operating a multi-cylinder fluid pump system, the method comprising: delivering fluid from a first cylinder at a target flow rate while a second cylinder is being filled, and delivering fluid from the first cylinder at a decreasing flow rate while delivering fluid from the second cylinder at an increasing flow rate, wherein the sum of the increasing flow rate and the decreasing flow rate equals the target flow rate, and wherein an operating parameter or condition of the multi-cylinder fluid pump system is modified in response to information about a condition of the fluid pump system. 